This invention relates to an insertion station for envelope-stuffing apparatus or for envelop-stuffing apparatus sections of mail handling apparatus. Frequently- used insertion stations of the prior art comprise a driving lever which swivels back and forth, in accordance with an operating cycle, and vertically to the feeding direction of the material to be inserted into envelopes. An axle arrangement is mounted thereto and is spring-loaded, perpendicularly to a base plate and parallel to the driving lever--the axles having insertion arms with an adjustment block mounted to each of them. Fingers of the insertion arms slide forwardly in an input direction in grooves of the base plate and are cyclically moved backwardly and upwardly above the base plate in a movement controlled by a finger roller guide. After the fingers reach the rear end of the finger roller guide, they transition from the backward location to forward input movement while at least one of the input finger rollers falls onto a substantially wedge-shaped insertion ramp for a gradual insertion of the input finger into the corresponding groove of the base plate.
The insertion stations of the prior art are generally time-tested, but one particular problem arises due to continuous increases in the operational speeds of mail handling apparatus. That is, the finger roller mounted onto an insertion arm abruptly leaves a finger roller guide at the end of a return movement in a cycle during which the finger roller guide is lowered onto and raised above the base plate upon the return movement. Tension of spring devices between the axle arrangement and the driving lever then causes the entire insertion-arm group to snap downwardly in the direction of the base plate. This movement causes the fingers of the insertion arms to noisily hit the grooves of the base plate and possibly bounce back such that the ends of the fingers reach above the material to be enveloped, and thus cause malfunctions.
It is a further disadvantage of apparatus of the prior art that the slack or play between the axle arrangement and the axle-ends of the insertion arms becomes uncontrollably larger after a comparatively short operation period such that irregular operation of individual insertion arms must be expected. Attempts have been made in apparatus of the prior art to correct this by adjusting the spring tension between the axle arrangement and the back-and-forth swivelling driving lever. These attempts, however, have not been satisfactory because of increases in the above-mentioned problems of noisy snapping movements of the insertion arms at the end of a return movement before the insertion movement.
It is an object of this invention to provide an insertion station of the type described above wherein increases in operational speed nevertheless allow reliable functioning, a longer operation span between required adjustments of assemblies, lower noise levels and lower maintenance.